Share this:

Watch on YouTube
This week nachbarnebenan shows how to use the KDE (and Windows) photo organizer digiKam. There is more to it, a second part will follow. I don’t know much about digiKam because I use Gnome Shell as my desktop environment and digiKam is made for KDE. It would run on my system, but I would have to install a lot of other stuff too. Linux users have a lot of desktop environments to choose from.

After a too long summer break I give you a preview of one feature in the next version of GIMP – the unified transformation tool. It combines the tools for moving, rotating, scaling, shearing and for changing the perspective in one tool with a nice and sleek user interface.

The UI design has been done mostly by Peter Sikking. He has also had his hands in the nice free selection tool design.

This unified transformation tool shall be used with visual feedback on the canvas. The old tool will stay around for work where numbers are important. So this is not a replacement but an addition.

There was no show for quite some time – and there will be a gap until the end of summer. I move back to Bremen – and that takes a lot of time and creativity away. But in Bremen I will have nearly 2 hours more time each day, because I can walk to school and don’t need to ride the famous Berlin S-Bahn Ring Line.

In the meantime I have a challenge for you! Present the place where you live to us – but look down on the sidewalk for that! The best results will be published in the GIMP Magazine #5 and of course here on the blog. The exact rules are below.

This Challenge is a perfect rip off from a challenge by Andrés (Twitter)(Website), an illustrator from Buenos Aires, in the now closed forum of Tips from the Top Floor. Make a mosaik of images of the sidewalks in your city and try to transport the atmosphere.
This is my take on the Silvio-Meier-Strasse around the corner from my flat in Berlin.

The Rules

Make a mosaic of at least 3×3 images.

All images have to be shot straight down

All images are in the same scale, use the same distance to the ground and the same focal length.

All images have to be linked to each other in their theme by being from one city, one journey …..

Publish your image online and post a link to it before September 1st in the comments to this blog post.

License your image as CC-BY or better and allow this site and the GIMP Magazine to publish your image under CC-BY (here) or CC-BY-SA (GIMP Magazine).

Rules 1 to 4 may be broken, 5, 6 and 7 have to be followed exactly.

You may download the template for my version from above or build your own one. You are free to make other forms than a square – circles or a spiral anyone?

The TOC

The video uses chapter marks, you can jump between TOC entrys!

00:00:00 Pause until end of August
00:02:05 A contest for you – introduction
00:03:42 The contest rules
00:04:50 My example
00:06:04 Selecting the images
00:08:00 Scaling down and exporting in Shotwell
00:08:40 Calculating the image size
00:09:30 Create the file
00:10:20 Save as XCF.gz – compressed to save space
00:11:05 Creating a “Contact Sheet” for reference with Imagemagick
00:13:00 Make a movable layer mask with “multiply mode”
00:16:00 Building a stack of layer groups and fill it with images
00:23:00 Filling images into the layer stack
00:26:45 Isolate the layer groups with “lighten only mode”
00:27:55 What do these layer modes do? Blackboard explanation
00:33:08 The last image – a Memory to Edith and Tina Wolff
00:34:30 Fine tuning the mosaic – exchange images
00:36:08 Adjusting contrast between the images with the curves tool
00:39:20 THE CHALLENGE
00:41:05 Variations: Soften the borders between fields
00:43:08 Final words about the Challenge
00:44:15 Exporting and scaling down for publication
00:45:45 End of video

Meet the GIMP and the GimpMagazine have been offline for hours today, because someone needed to download all the content in parallel. I have no idea if this is flattering or an attack. I have blocked the IP and will re-open it after I got a mail from you

This was simply too much load for the machine.

Edit: Now the machine should be able to keep up, I limited the memory consumption of Apache. It will be slow, but will stay up.

The next video is in the works, I can start editing tomorrow after the grades meetings are over. Lots of stuff happening here, more in the show.

In the last Episode I looked under the hood of JP(E)G and PNG. This time it gets a bit more practical – which is better for what?

I tackle two examples from the GIMP Magazine web site and test, if they would be better saved as JPG or PNG. The Plugin “Save for Web” is really usefull for this task.(The image for this blog entry is a PNG by the way, showing JPG compression artifacts. As a JPG it would be five times the size. )

I “developed” a method for comparing two layers – just set the top layer mode to “difference”, make a new layer from visible and check that with the threshold tool for pixels, that are not completely black. After locating the problematic zones in an image with this tool, one can decide what settings are “good enough”.

Conclusion: It depends. It depends on the file, your use case, your level of “good enough” and your compassion for people on a mobile device in EDGE-Hell.

The show starts with a little extension of the last show, Pascal mentioned some options for saving a JPG file that I had overlooked.

The TOC

00:00:00 Start of video
00:01:00 Progressive mode in JPEG
00:04:09 Progressive mode is not fully supported by browsers
00:04:23 Optimized mode
00:05:56 Baseline?
00:06:17 The quality setting
00:07:09 GIMPMagazine and MTG header image – PNG or JPG?
00:09:23 Checking for quality loss in JPG
00:10:03 Comparing two layers with difference mode
00:10:48 Using the histogram for analysis of the amount of difference
00:11:25 Locating the differences
00:13:50 Trying 85, 75 and 90 as quality settings
00:16:13 When in doubt, compare different settings
00:16:36 Save your work as XCF.GZ
00:17:12 Second example – a drawing
00:19:56 Conclusion
00:23:19 Stay at 4:4:4 for subsampling with photos
00:25:16 Final words of wisdom
00:26:07 End of video

Darktable, the RAW converter and management program, has released a new version, 1.2. Cool stuff about camera specific noise and much much more! And they seem to get masks …..

Do you have a scanner, paper documents to process and run Linux? Then Konrad Voelkel has something for you: “After having bought a new flatbed scanner, I re-investigated how to scan and OCR pdfs, how to produce DJVU files that are incredibly small and how to get metadata right. It turns out what I really ever wanted was to create PDF/A compliant documents (I just didn’t know what PDF/A was before). But let me explain the details after presenting you the quick solution. At the end, I have a shell script that scans directly to PDF/A.”

The Rule Of Thirds on Steroids – Alfred Eisenstaed’s compositional system in an analysis of some of his images and a Degas painting. I am not sure if this is over-analysed or not, but it’s an interesting read.

The last episode was for absolute beginners, this one is for Geeks. I try to explain (and understand on the way) how images are stored in PNG and JPEG files. PNG (pronounced “PING”) does this lossless, the image can be retrieved in the same quality as the original. PNG works wonders with graphics with a lot of lines and clear colour areas, comics and logos for example, but it creates monster files out of photos and similar images. JPEG looses details, aquires artefacts and generally mangles the image. But it has so beautifully small files and the losses are in most cases invisible – except in the area where PNG is good. So both have their niche to live in.

How is this done? I try to explain this without the math, using analogies, plaing with GIMP to reenact some stages and reducing the complexity a lot. If you want to know the exact facts, read up in Wikipedia, which was also my source of information, or look for other sources. I hope that I never crossed the border between simplification and telling wrong stuff – but I am really not sure. The math is really over my head, last time I had to tackle such a level a Pentax ME Super was still a new camera model. I am happy about any comments that improve my understanding – and all other comments too.

Here are the links for this Tuesday – a bit late, I managed to set the timer the wrong way…..

[UPDATE] I forgot one important link: A new version of G’MIC, numbered 1.5.5.1, has been released. It is really impressive. And David Tschumperlé’s car broke down and leaves him in a bad financial situation. David is the guy behind G’MIC, you know what to do with his donation buttons, don’t you?

Patrick David has a close look at skin faults. With Blue Light. And provides even a script for that. After reading that you know why RED light is more romantic…..

Do you remember LightZone? A really good program for Linux and MacOS, but proprietary code? No costs but threatening to charge in the future? It is now Free Software! Check it out – I want some opinions if I should go into it!

GIMPHELP.ORG has a script collection that has all compatibility problems with 2.8/2.9 ironed out. And more stuff.

Lens Fun is a library for correcting Lens Errors in digital images. And there is a plugin for GIMP to correct lens distortions using that plugin.